This invention relates to a dialysis membrane of regenerated cellulose.
Dialysis membranes of regenerated cellulose are known and have been used extensively in artificial kidneys. Above all, it has been especially preferred to use dialysis membranes which have been regenerated from cuprammonium solutions, i.e. a regenerated cuprammonium cellulose. Prior processes for the production of such membranes are practically no different from the processes used for many years to produce cellulosic films. A description may be found, for example, in "Ullmanns Encyclopadie, der technischen Chemie", 3rd Edition, 1960, Vol. 5, pages 204 ff and Vol. 11, pages 260 ff.
These known dialysis membranes, which consist of regenerated cellulose according to the cuprammonium process, are characterized by a suitable ratio of hydrodynamic permeability to diffusive permeability, by such a pore size that the passage of protein substances and other high molecular weight components of the blood are prevented, by a good compatibility with blood as well as by good mechanical properties for use in dialysis equipment.
When using dialysis membranes produced from other materials, one frequently finds a higher hydrodynamic permeability (water permeability) but a lower diffusive permeability (for molecules of intermediate molecular weight). These other known dialysis membranes are made from polyacrylates, polysulfones, polyvinyl alcohols, polycarbonates, cellulose acetate and cellulose nitrate. The cellulose acetate and cellulose nitrate are more or less strongly saponified. These types of membranes are preferably used for blood filtration treatments.
Earlier in this art, blood filtration was introduced as a method of treatment for dialysis patients suffering from high blood pressure. For the reinfusion of large amounts of fluid into the human blood stream, use was made of membranes for the dialysis treatment which exhibited a high hydrodynamic permeability while accepting the disadvantage of lesser diffusive permeability exhibited by the known types of membranes.